Pump



July 7, 1964 N. K. STENBERG PUMP Filed June 1, 1961 FIG' INVENTOR. NYYRlKKl K. STENBERG BY flurw i ATTORNEY;

skc United States Patent 3,139,829 PUMP Nyyrikki K. Stenberg, Roslyn, Pa., assignor to Fischer & Porter Company, Warminster, Pa., a corporation of Pennsylvania Filed June 1, 1961, Ser. No. 114,188

1 Claim. (Cl. 103-37) This invention relates to pumps and has particular reference to a pump arranged to deliver liquid at a very low rate.

In a situation typified by a water chlorination system there arises the necessity for feeding to a flowing body of liquid quite minute quantities of another liquid. The latter liquid is desirably fed more or less uniformly to maintain a substantially constant composition of the mixture. For example, considering chlorination of water, it is commonly desirable to provide means for determining residual chlorine content of the water at some point in the system which may be remote from the point of introduction of chlorine and at which the major portion of the chlorine may have been taken up by reaction with impurities in the water. In such system at the point where residual chlorine is to be measured a continuous flowing sample of the water is bypassed to chlorine measuring apparatus. The amount introduced to such measuring apparatus is generally small, and for proper operation of the measuring apparatus it is usually desirable to introduce small quantities of a relatively concentrated buffering solution, such as a sodium acetate-acetic acid, which may also contain potassium iodide. The rate of feed of the latter solution may be only at the rate of a fraction of a cubic centimeter per minute. The low rate of feed of a concentrated solution is desirable so that a supply bottle or tank may be refilled with the concentrated solution only at greatly spaced intervals of time. The buffering solution is desirably fed continuously so that the buffer concentration in the water undergoing measurement will be substantially constant at all times. Such slow and continuous feed has been accomplished by providing diffusion of the treating liquid through a porous element, but this practice has various disadvantages.

In a situation such as that outlined it would be desirable to provide the feed by means of a pump metering the added liquid, but pumps delivering liquids in the very low quantities above indicated have generally been quite unsatisfactory, trouble being particularly involved in the matter of operation of valves at the low rates of flow.

It is the general object of the present invention to provide a pump of slowly reciprocating type free of valves and capable of providing a low average rate of flow. While the displacements of the pump are intermittent, provision is made in accordance with the invention to smooth out the delivery by feeding of the intermittent increments of the liquid to a wick which is immersed at its delivery end in the liquid to which the addition is made, gradual flow through the wick eliminating the pulsations in the supply thereto.

The pump arrangement is applicable to many uses where requirements similar to those discussed must be met. The attainment of the general objects as well as other objects relating to matters of construction and operation will become apparent from the following description, read in conjunction with the accompanying drawing in which:

FIGURE 1 is a vertical sectional view showing the pump and its associated elements; and

FIGURE 2 is a plan view of the same.

In a preferred form of the invention the pump comprises a block 2 which may be of a plastic resistant to corrosion by the liquid involved, although it may be of a suitable corrosion-resistant metal. Within this block ice there is provided a small reservoir 4 for the liquid to be pumped, which reservoir is supplied with the liquid through a tubing connection indicated at 6 receiving the liquid from a main supply reservoir which is of a conventional type maintaining the liquid surface at the level L in the reservoir. The block is also provided with an outlet passage 8.

A bore extends transversely of the reservoir 4 below the level L and has packed therein a tube 10, which may be of metal or plastic, providing a cylinder associated with packing 12 at its outer end through which there extends a piston 14 having a sliding fit within the tube bore. The tube is provided with a port 16 furnishing communication between the reservoir 4 and the cylinder bore, the port 16 being submerged in operation. The piston 14 is provided with a head 18 internally threaded to receive an extension 20. The effective length of the piston assembly is adjusted by rotation of the piston to move it inwardly or outwardly relative to the extension 20, the assembly being secured in adjusted position by a lock nut 22. The extension 20 is pivoted at 24 to an eccentric strap 26 embracing an eccentric 28 mounted on the shaft 30 of a motor 32. This motor will usually be of a synchronous or induction type with reduction gearing built therein so that the shaft 30 rotates at a low speed which may typically be of the order of around 20 revolutions per minute. Because of the synchronous or induction type of motor used, driven by the usual alternating supply, the shaft 30 will be rotated at a substantially constant rate.

At its left-hand end as illustrated the bore of cylinder 10 communicates with the space 34 from which there extends upwardly a bore 36, the bore being enlarged at its upper end to receive a sleeve 38 which desirably has its upper end cut at an angle 40 and slotted as indicated at 41 in a direction extending along the slope to receive the upper end of a wick 42 of a fibrous material such as cotton which is held in the slot 41 as by the formation of an enlarged knot at its upper end. The wick 42 extends downwardly through the bore 8 and into a tube 44 extending as a continuation of the bore 8. The lower end of this wick desirably projects into the liquid to which the pumped liquid is to be delivered.

A cap 46 closes the upper end of the reservoir 4 and a similar cap 48 is provided to close the space surrounding the upper ends of the bores 8 and 36 and the sleeve 38, the caps being provided to minimize evaporation and exclude dirt. The two caps are interconnected by a tube 50 for pressure equalization.

Operation is as follows:

As the piston 14 moves outwardly, clearing the port 16, liquid from the reservoir will flow into the cylinder and follow the piston. As the piston then moves inwardly the liquid is reversely displaced, flowing outwardly through the port 16 into the reservoir and, to a minor extent, into the bore 36. However, except to the extent of transient movements of the liquid which are not of significance at the low rate of piston movement, nothing occurs until the piston moves to a position to cut off the port 16. As the piston then continues to move toward the left the liquid trapped at its left is forced upwardly through the bore 36 and into the sleeve 38 to come in contact with the wick and possible overflow to the extent that a drop of liquid will Wet the wick and be conducted by it downwardly into the liquid to which the addition is to be made. Upon the reverse stroke of the piston the liquid level in the bore 36 drops and when the port 16 is again opened communication is established between the reservoir 4 of the bore 36 to equalize the levels, the further movement of the piston repeating the cycle as described above.

Since the effective part of the stroke of the piston occurs after cut oif of the port 16, and ends with the extreme left-hand dead center position of the piston, it

will be evident that the corresponding piston movement measures the delivery of the liquid in a single stroke. For minimum delivery the effective part of this piston stroke is secured when the adjustment at 18, 20 is such that the 'displacement-juSt mentioned will move the liquid in the bore 36 barely to the position at which it will contact the --wick "and be absorbed by capillary action. 'A minute "amount ofliquid may thus be delivered. If more liquid --is*to be delivered on each stroke, the piston is elongated by adjustment of its effective length at 18 and 20 so that there is longer range of the stroke between cutting off of i the port 16 and left-hand dead center. A drop of substantial 'sizemay thus be forced out and about the wick so as to run down the wick being absorbed during its flow by capillary action, with gradual displacement of the liquid at the lower end of the wick which thus passes into the liquid'being treated. It may be noted that there is no need in this arrangement to provide packing between the cylinder wall and piston at their left-hand ends, a free runningclearance being provided. Under static conditions or extremely slow movement of the piston this running clearance might permit a back flow of liquid relative to the piston to prevent substantial rise in'the bore 36; but with a suitably small clearance of no more than a few thousandths of an inch and with reasonable rates of cycle repetition this back flow is at a rate small in comparison withthe piston displacement so that a pumping action occurs. The pump is'for practical purposes a posi- 'tive one through not strictly so. As will be evident from the figure, the head pumped against is very small.

The action of the wick is such as to smooth out the flow'as this takes place at the delivery end of the wick. The gravity flow through the wick becomes quite uniform "a short distance from its point of reception of the liquid drops.

The pumping rate of the liquid depends, of course, upon the maintained level L and this level may be adju'sted at the liquid supply; but it is more desirable to 'adjust the pumping rate by adjustment of the effective piston' length, its complete stroke being, of course, con- "stant.

The provision of the notch 41 at the lower end of the bevel 40, and through which notch the wick passes, provides substantially complete absorption of each drop by the wick avoiding the passage of individual drops downwardlyalong the wall of the bore 8.

"It'will be evident that various changes in details of 'construc'tion'and operation may be made without departing from the invention as defined in the following claim.

What is claimed is:

Pumping means for the delivery of small quantities of liquid comprising means providing a reservoir for the liquid to be delivered, a cylinder having a port providing continuous liquid communication between the reservoir andthe cylinder, means providing an upright passage communicating at a lower portion thereof with said cylinder and having at an upper portion thereof a discharge opening at a level above that of liquid in said reservoir, a piston in said cylinder, means reciprocating said piston, said means effecting in a working stroke of the piston, cutting off of said port and then displacement of liquid in said cylinder and upwardly in said upright'passage to the discharge opening thereof, and a wick transverse said discharge opening above the level of liquid in said reservoir to absorb a small quantity of upwardly displaced liquid and conduct the same gradually to a point of utilization during periods between working strokes of the piston, said "Wick being 'out "of contact with liquid in said upright passage except'during the upright displacement thereof during working strokes of the piston.

References Cited in the'file of this patent UNITED STATES PATENTS 976,148 Caps Nov. 22, 1910 I 979,101 Scott Dec. 20, 1910 1,241,174 Von Woltfradt Sept. 25, 1917 1,308,417 Gustafson et al July 1, 1919 1,318,558 Held Oct. 14, 1919 1,323,603 Manzel Dec. 2, 1919 1,683,617 Hennessy Sept. 11, 1928 1,695,501 Optiz Dec. 18, 1928 1,776,938 Turner Sept. 30, 1930 1,784,977 Seitz Dec. 16,1930 1,878,317 Picard Sept. 20, 1932 2,044,044 Anthony June 16, 1936 2,141,022 Rotter Dec. 20,-193 2,778,449 Schiesswohlet'al. Jan. 22, 1957 2,869,467 :Limpert et al J an. 20, 1959 2,968,963 Hazlett Jan. 24, 1961 3,011,592 Ross Dec. 5, 1961 FOREIGN PATENTS 194,309 Germany Jan. 18, 1908 641,834 ;Great Britain -Aug. 23, 1950 238,898 Switzerland Dec. 3,1945 

